Float operated signalling device

ABSTRACT

The invention is concerned with a float operated signalling device of the kind in which a magnet follows the movement of a float in a liquid container and operates signal controls through a non magnetic wall. An open topped pan having a drain opening is attached to the magnet/float assembly and an auxiliary liquid supply is provided for depositing liquid into the pan at a rate greater than that at which it can drain out of the pan. When the pan contains liquid the float is dunked below the liquid in the container so that the magnet operates the signal controls for test purposes.

United States Patent @191 Innes et al. I

154] FLOAT OPERATED SIGNALLING DEVICE [75] Inventors: Robert Innes, Beaconsfield; Ernest- Albert Morrison, Gerrards Cross, both of England [73] Assignee: Roland Trist Controls Limited,

Slough, Buckinghamshire, England [22] Filed: April 26, 1971 [21] Appl. No: 137,443 7 [30] Foreign Application Priority Data May 8, 1970 Great Britain ..22,397/70 [52 US. Cl. ...73/1 'R, 73/3225, 73/D1G. 5,

340/410 [51] Int. Cl ..G0lf 25/00 [58] Field of Search ..73/l R, 305, 307, 314, 319,

73/322.5,'313, DIG. 5; 340/410 [56] I 1 References Cited UNITEDSTATIESPATENTS 2,370,099 2/1945 Werder.....' .,....34o 410ux 1451 Jan. 16,1973

2,547,526 4/1951 Hilliard ..340/4l0 UX 2,588,761 3/1952 Raby ..340/4l0 UX 2,798,214 7/1957 Rowell 4 ..340/4l0 3,014,205 12/1961 Boehm ....340/410 3,060,717 10/1962 Howe ..73/1 R Primary Examiner-Louis J. Capozi Assistant Examiner-Joseph W. Roskos AttorneyHolcombe, Wetherill & Brisebois 57 ABSTRACT The invention is concerned with a float operated signalling device of the kind in which a magnet follows the movement of a float in a liquidcontainer and operates signal controls through a non magnetic wall.

An open topped pan having a drain opening is attached to the magnet/float assembly and an auxiliary liquid supply is provided for depositing liquid into the pan at a rate greater than that at which it can drain out of the pan. When the pan-contains liquid the float is dunked below the liquid in the container so that the magnet operates the signal controls for test purposes.

9 Claims, 2 Drawing Figures PATENTEDJAHSIQZS 7 3.710.612 SHEET 2 [1F 2 boiler. The device is of the kind having a float which follows changes in the liquid level in the container, the

pump through a conduit when replenishment is required. The pump may, for testing, supply the water through a shut-off valve to a duct which passes into the boiler and terminates at a nozzle which is arranged to direct a jet of water into the auxiliary container. The valve is opened to allow thewater to flow through the duct into the auxiliary container during testing but at float being mechanically connected to a magnet which 7 thus follows the movement of the float and is movable to and fro inside but adjacent to a non-magnetic wall part of the container. Magnetically operated switch contacts or other signal controls are mounted on the outside of the wall part and are actuated by the changing magnetic field-emanating from the magnet as the magnet moves to and fro, usually up and down.

- It is desirable, with this type of system, to be able to I test whether a device is functional particularly if it incorporates a switch used as a low level alarm or as a burner cut out. For test purposes it is necessary to movethe magnet,'and'consequently move the float into the liquid, without necessarily changingthe liquid level.

One previous proposal for meeting this problem has involved the provision of a'magnetic armature connected to the magnet together with a magnetic actuator which can be used to influencethe armature through a nonmagnetic wall part of the container to move the magnet and float and test the device. This is not entirely satisfactory'for two reasons. First, the system has-to be increasedin size to accommodate the extra non-magnetic wall part and armature and, secondly, the armature may retain some magnetism and this may influence 'theco-operation between the magnet and signal concontainer, and there being means for charging liquid into the auxiliary container at a rate greater than that at which it can drain out ofthe auxiliary-container so that when liquid 'is so supplied to the auxiliary container the effective weight of the float and associated parts is increased and the float sinks, in use, in the liquid in.the main container, this movement of the float being followed by the magnet which thus movesand actuates the signal controls for test purposes.

When the supply of liquid to the auxiliary container is stopped, the liquid in the auxiliary container drains out into the main container and consequently the float and associated parts assumes its previous weight and equilibrium is again restored for normal operation.

The liquid supplied to the auxiliary container during the testing operation will enter the main liquid conother times the valve will be closed. The valve may be solenoid operated, thus making remote controlled manual or automatic testing possible. In any'case, the system remains completely sealed duringtesting;

The auxiliary container may be in an open topped pan having at least one perforation in its wall, rather in the manner of a colander. This auxiliary container may be mounted directly on top of the float or above the float on a stem or rod by means of which the float is connected to the magnet.

One example of a boiler'installation incorporating a multiple level switch device in accordance with the present invention is illustrated in the accompanying drawings, in which:

F IG. 1 is a diagrammatic elevation of the installation; and, I

P16. -2 is a section through the switch device.

As shown in FIG. 1, the installation comprises a boiler 3 containing water 4 and arranged to be replenished by means of a pump 5 which pumps water 1 through conduits 6 and 7 through a non return feed can run out of the auxiliary container into the main.

check valve 8 into the boiler.

The switch device comprises a cage 9 which is welded or. otherwise sealed into the vtop wall of the boiler 3, and contains a float 10 on the lower end of a stem 11. The upper end of the cage 9 is provided with a flange l2 to whicha closure .plate 13 is bolted with the interposition of a gasket 14. The closure plate 13 supports a switch-housing 15 incorporating a non-magnetic stainless steel tube 16 the lower end of which has screwed onto it a centrally perforated guide 17. The stem 11. extends up through the central aperture in the guide 17 and into the tube 16 where it supports a permanent bar magnet 18.

Mounted inside the housing 15 and at fixed different heights alongside the tube '16 are two magnetically responsive switch units 19 and 20, although more than two units may be provided at choice. These units may be conventional magnetic reed switch units, or moving magnet switch units, such as that described in our British Pat. specification No. I 153297. 'The switch units 19 and 20 are connected by' external leads to an appropriate indicating and/or automatic control I system.

tainer and it follows that the supply of liquid to the auxv iliary container can be provided by a simple redirection of the liquid feed to the main container 'whentesting is The cage 9 carriesa baffle 21 spaced beneath its lower open end to inhibit rising bubbles from entering the cage and disturbing the'float, and is provided with vent holes 22 abovethe upper water level to equalize the pressure within the cage and thusensure that the liquid level remainsthe same inside and outside'the cage. When the closure plate 13 and associated switch housing are-undoneand'removed from the cage 9, the

guide 17 prevents the magnet 18 from dropping right proaches the switch unit- 19 and when the limiting lower level illustrated in full lines in'FIG. 2 is reached the switch unit 19 is actuated. This actuation operates a warning to indicate to the operator that the boiler requires replenishment, or alternatively actuates an automatic control system. The pump 5 is started and water is pumped through the valve 8 into the boiler. As the water level in the boiler risesthe float carries the magnet 18 up until the dotted line position in FIG. 2,is reached whereupon the switch unit 20 is actuated.

Actuation of the unit 20 provides a further indication to the operator that the replenishment is complete so that the water supply is cut off, or alternatively causes the automatic control system to stop the pump 5.

At intervals in use it is desirable to check the operation particularly of the lower level switch unit 19. For this purpose an open topped pan 23 having a drain opening 24 is mounted on the stem 11 above the float 10. An auxiliary water supply conduit 25, incorporating a valve 26, leads from between the pump 5 and the check valve 8 through a coupling 27 to a conduit 28 within the closure plate 13. The conduit 28 terminates in a projecting pipe nozzle 29 which is directed downwards to discharge into the pan 23.

When it is required to test the operation of the switch unit 19, the pump 5 is started and the valve 26 is opened. The pressure drop across the feed check valve 8 is appreciable by virtue of a narrow orifice throttle 30 inserted on the pump side of the check valve 8. As a result water is pumped through the conduits 25 and 28 and the nozzle 29 into the pan 23. The rate of discharge of water into the pan is greater than the rate at which it can drain away through the drain opening 24 and accordingly the weight of the pan, float and magnet un'it increases and as a result the float is dunked below its buoyancy position in the water 4. The pan 23 will hold sufficient water to enable the float to be dunked so low that the magnet 18 will reach the lower level position illustrated in full lines in FIG. 2 so that the switch unit 19 is actuated. Once the operator is satisfied with the test, the pump 5 is stopped and the valve 26 is closed. Any water remaining in the pan 23 then drains out through the drain opening 24 into the boiler and the float and magnet readopt their equilibrium positions.

We claim:

l. A float operated signallingdevice of the kind commagnet coupled to and following movement of said float and actuating signal controls through said nonmagnetic wall part, wherein an open auxiliary liquid container is mounted above and connected to said float, said auxiliary container having an open drain outlet through which liquid can run out of said auxiliary container intosaid main container, and there being meansfor charging liquid into said auxiliary container at a rate greater than that at which it can drain out of said auxiliary container so that when liquid is so supplied to said auxiliary container the effective weight of said float and associated parts is increased and said float sinks in the liquid in said main container, said movement of said float being followed by said magnet which thus moves and actuates said signal controls for test purposes.

2. A device according to claim 1, wherein said auxmagnet is reciprocable and which is mounted together with said signal controls on a removeable closure for the upper end of said cage.

5. A device according to claim 4, wherein said auxiliary container can be charged with liquid through a conduit extending through said cage closure.

6. A device according to claim 4, wherein there are two sets of signal controls actuable individually when said magnet is at different positions along the said tube.

7. A liquid container installation comprising a main liquid container fitted with a signalling device according to claim I, and a conduit for discharging liquid into said auxiliary container, said conduit being connected to a source of liquid under pressure and incorporating a check valve.

8. An installation according to claim 7, wherein said conduit is a branch from a main supply line for said main liquid container.

9. An installation according to claim 8, wherein said main supply line incorporates a non return check valve downstream of said conduit branch and a throttle between said check valve and said conduit branch. 

1. A float operated signalling device of the kind comprising a main liquid container having a non-magnetic wall part, a float within said main liquid container and a magnet coupled to and following movement of said float and actuating signal controls through said non-magnetic wall part, wherein an open auxiliary liquid container is mounted above and connected to said float, said auxiliary container having an open drain outlet through which liquid can run out of said auxiliary container into said main container, and there being means for charging liquid into said auxiliary container at a rate greater than that at which it can drain out of said auxiliary container so that when liquid is so supplied to said auxiliary container the effective weight of said float and associated parts is increased and said float sinks in the liquid in said main container, said movement of said float being followed by said magnet which thus moves and actuates said signal controls for test purposes.
 2. A device according to claim 1, wherein said auxiliary container is an open topped pan having at least one perforation in its wall.
 3. A device according to claim 2, wherein said auxiliary container is mounted on a stem which extends upwards from said float and carries said magnet at its upper end.
 4. A device according to claim 3, wherein said float moves upwards and downwards within a cage which is fixed in position relative to said main liquid container, and said non-magnetic wall part is a tube in which said magnet is reciprocable and which is mounted together with said signal controls on a removeable closure for the upper end of said cage.
 5. A device according to claim 4, wherein said auxiliary container can be charged with liquid through a conduit extending through said cage closure.
 6. A device according to claim 4, wherein there are two sets of signal controls actuable individually when said magnet is at different positions along the said tube.
 7. A liquid container installation comprising a main liquid container fitted with a signalling device according to claim 1, and a conduit for discharging liquid into said auxiliary container, said conduit being connected to a source of liquid under pressure and incorporating a check valve.
 8. An installation according to claim 7, wherein said conduit is a branch from a main supply line for said main liquid container.
 9. An installation according to claim 8, wherein said main supply line incorporates a non return check valve downstream of said conduit branch and a throttle between said check valve and said conduit branch. 